Two nodules of hepatic adenomatous hyperplasia (AH) resembling focal nodular hyperplasia were found in two patients with cirrhosis or chronic active hepatitis. Imaging techniques suggested that the nodules were hepatocellular carcinoma. Pathological examination showed that the nodules (approximately 1.0 cm in diameter) were clearly demarcated from the surrounding liver tissue, and contained foci of scar-like fibrosis in the centre of the nodules. Microscopically, they contained portal tracts and fulfilled the criteria of AH. A large number of arteries were present in the central scar-like fibrosis as well as in the parenchyma of the nodules. There were foci of mildly atypical hepatocytes in one nodule but no cellular atypia in the other. Morphometric analysis showed that the cumulative luminal area of arteries per unit area was much greater in the nodules than in the extranodular liver tissues, while the cumulative luminal area of portal veins per unit area was much less in the nodules than in the extranodular liver tissues. Although the pathogenesis is unclear, these nodules might have developed through localized vascular changes associated with chronic liver disease, may have arisen from pre-existing arterial malformation, or may represent the early stages of angiogenesis in hepatocarcinogenesis.